Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
sach kem » hanh kem
hieu va » lieu va, hieu qua
duc van » duc va, duc tan, duc manh
cac duc » cac du, cao duc, cac dac
hieu ve » hieu van
sach ki » sach kinh, sach bai, sach doi
nang xa » nang x, lang xa, nang ma
vi cua » vai cua, di cua
cua cu » cua chu, cua cau, cua su

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach ki) OR (sach kem)) nang xa hoi. ((hieu ve) or (hieu va)) cac duc van hanh vi cua cu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ki) OR (sach kem)) nang xa hoi. ((hieu ve) OR (hieu va)) cac duc van hanh vi cua cu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ki) OR (sach kem)) nang xa hoi. ((hieu ve) or (hieu va)) cac duc van hanh vi cua cu".
• Adding a wildcard symbol may retrieve word variants: te ((sach ki) OR (sach kem)) nang xa hoi. ((hieu ve) or (hieu va)) cac duc van hanh vi cua cu*.